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Showing results for tags 'Forth Assembler'.
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I decided to move my explorations into TurboForth Assembler to a different thread (this one) rather than hijacking another thread. My post here (http://www.atariage....ost__p__2415039) alludes to my current project, viz., implementing Tursi's TMS9900-Assembler-coded 14-bit countdown timer (http://www.atariage....ost__p__2021341) using the TMS9901 Programmable Systems Interface and based on Thierry Nouspikel's code ("TMS9901" link at http://www.nouspikel...titechpages.htm). My two Forth words have the same name as Tursi's TMS9900 Assembler code: INIT01 to start the timer and READ01 to get its current value. My TurboForth Assembler code follows: ASM: INIT01 ( --- ) R12 R2 MOV, \ Save return address R12 CLR, \ CRU base of the TMS9901 0 SBO, \ Enter timer mode R1 $3FFF LI, \ Maximum value R12 INCT, \ Address of bit 1 R1 14 LDCR, \ Load value R12 DECT, 0 SBZ, \ Exit clock mode, start decrementer R2 R12 MOV, \ Restore return address ;ASM ASM: READ01 ( --- n ) R12 R2 MOV, \ Save return address R12 CLR, \ CRU base of the TMS9901 0 SBO, \ Enter timer mode SP INCT, \ Make space on stack to leave timer value *SP 15 STCR, \ Read current value (plus mode bit) and put on stack *SP 1 SRL, \ Get rid of mode bit 0 SBZ, \ Exit clock mode, decrementer continues R2 R12 MOV, \ Restore return address ;ASM Both words seem to compile OK. INIT01 appears to work, but I cannot tell for sure because executing READ01 causes a stack underflow, which baffles me. Any ideas as to what is wrong? ...lee
Mark (or anyone)... I cannot find any documentation about using the TurboForth word JOYST except in the TF v1.1 Release Notes: JOYST ( jstick# -- value) modified to invert the returned value, making decoding much simpler. JOYST also resets the screen blanking counter in the console interrupt routine to prevent screen blanking. Unfortunately, this is not very helpful to me. In TI Forth, three values are left on the stack (ASCII, xpos, ypos). I have no idea how to use TF's word. I cannot even get it to respond with a value other than 0 when I use it in a loop in the emulators for joystick #1, i.e., 1 JOYST . I am trying to use the keyboard emulation of joystick #1 (Q,W,E,R,S,D,Z,X,C). ...lee